Current practice in forest tree breeding relies on phenotypic selection, a time-consuming process. Genetic analysis of woody plants is hindered by the long generation times, non-domestication, high levels of genetic diversity and large size of the plants in question. Additionally, little is known about the mode of inheritance for most traits of interest in forest trees. Tree breeding is made more difficult as, in addition to the long generation times, certain traits of interest such as wood properties change during growth and maturation. Methods that allow the early selection of genetically superior individual trees would be of value in programs to improve tree stock.
The use of isozyme markers has been used to explore genetic variation in forest tree populations. The method is limited, however, by the small number of enzymes for which assays are available (Conkle 1981). The scope of genetic analysis for forest trees was extended by the development of restriction fragment length polymorphisms (RFLPs). However, the analysis of RFLP markers is laborious and limiting.